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Ask the gardener: Silver Birch

Bill Blackledge's advice on how to care for Silver Birch trees...

Warton's Bill Blackledge is one of the county's most popular and sought after gardeners. If it's green and needs watering, Bill can tell you about it. He has been answering BBC Radio Lancashire listeners' queries for over thirty years, which means he's been there nearly as long as the transmitter!

His knowledge is encyclopedic. After training at the under the then Ministry of Agriculture, Bill spent over twenty years at the Department of Biological and Environmental Services at Lancaster University. Now, he's a regular course tutor at Alston Hall, Longridge and Lancaster Adult College.

For three decades, Bill has travelled the county with fellow judges as a regional judge for North West in Bloom.

So, whatever the problem, we like to think Bill can sort it out... at least that's the theory!

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Susan asks...

I was wanting to plant three silver birches together to form a multistemmed tree, does this effect the growth of the trees? I don't want them to get too high and have heard planting silver birches together reduces the trees ultimate height. Can you recommend a suitable variety for planting in this way? Thanks

Bill replies...

If you intend to plant in the same planting hole two to three Silver Birch Susan the species I would recommend is Betula Ermanii. This species is very hardy, has beautiful peeling white bark tinged with pinkish cream and the delicate foliage turns a beautiful bright yellow in the autumn but, it will reach a height of 4 to 5 metres in approximately 10 to 12 years if you start with container grown trees approximately 2 to 3 feet high. You mention that these trees will form a multi-stemmed tree but you can actually buy a single multi stemmed tree which has had its main leader cut out causing lateral branches to grow and this tree will produce a smaller but spectacular tree, and again you can use Betula Ermanii or the Himalayan Birch which also has a fine white peeling white bark and makes an excellent multi-stemmed tree. Of the two multi stem cultivars I personally would recommend the Himalayan Birch (Betula Utilis Jacquemonti).

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Steve Jolly asks...

I planted a copse of 15ft high Silver Birch trees in March. The dozen betula utilis jacuemontii have not started to bud at all yet, while the two betula ermanii planted within the same group are in full leaf. Is this normal or should I be concerned?

Bill replies...

Your Betula Utilis Jacquemonti Himalayan Birch Trees should now be Steve be in full leaf (May) and if you have kept an eye on the watering it would be worthwhile to contact your Tree Supplier and I am sure that a reputable supplier will replace your trees. There is obviously nothing wrong with the soil as your other Birch trees are in full leaf.

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Sheila asks...

My sister bought me a silver birch tree as an anniversary gift. We do not have room for a huge tree and we want to patio our garden so we have put the tree in a large pot. Will this harm it or will it just stunt the growth which is what we would like to happen?

Bill replies...

You can Sheila restrict the growth of Silver Birch by growing them in large containers but if your Silver Birch is a large woodland species, it can grow to a height of fifty to sixty feet, this will prove very difficult. There are however more compact weeping species of Silver Birch which can be grown in large containers and it would be worthwhile finding out from your sister which species she purchased.

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Karin Billington asks...

I have a large Silver Birch in my front garden which has a couple of dead branches at higher levels and the twigs snap off quite easily in windy conditions. The crown and higher level branches have been pruned at some point although I am not sure if this was done professionally. Can I do anything to help revive this tree or has it reached the end of its natural life and should I think about having it removed? If that were the case I would want to replace like for like, so what is the largest size birch I would be able to plant in the same space?

Bill replies...

I feel Karin it is important that the dead branches are cut off your Silver Birch as they could quite easily break off and cause damage. If you feel that your tree needs further pruning then this needs to be done late autumn time. Birch do bleed profusely if pruned when actively growing and this can seriously weaken the tree. With regard to keeping your tree I feel that it would be far better for you to receive on the spot advice from a qualified tree surgeon. If you decided to replace your tree the common Silver Birch (Betula Pendula) will grow to a height of thirty five to forty feet but, there are other smaller species such as Betula Pendula Youngii and this tree has weeping branches which touch the ground. Betula Fastigiata is column shaped and is far better for small gardens. I also feel that it is important that you do not replant a new Birch in exactly the same soil and same position.

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Dan Taylor asks...

I have recently moved house and am now in the middle of a major garden overhaul. Most of the rear garden was covered in gravel and I want to turf it all. However having removed said gravel I was surprised to find the very knobbly root system of my silver birch. Obviously with this root system I am never going to have a very level lawn and unfortunately have decided to remove my 40ft silver birch. Will this tree have a tap root? What would you suggest I do? Thank you.

Bill replies...

Before you cut down your forty foot Silver Birch Dan it maybe worth contacting your Local Authority to check if there is a preservation order on the tree. If this is the case and you are not allowed to cut your tree down. The other option would be to cover the roots of the tree with a good layer of top soil before laying down your turf. You will find it will be impossible to turf very close to the tree and you will need to select a turf which will grow under the shade of the tree and I am afraid that in time it is quite possible that odd roots may resurface.

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Tony asks...

Hi, could you tell me how to best 'kill' a silver birch and how long it may take before I can start digging it out old roots come out easily. Could you recommend a near replacement for the silver birch that would not grow as tall?

Bill replies...

If you do need to remove your Silver Birch Tree Tony you would be far better employing a Tree Surgeon to cut down the tree and after the tree has been cut down you can then apply a product such as Root Out to kill the root stump. I would not recommend using a weedkiller to try and kill your tree because, as the end of the day, you are still going to have to cut your tree down which by this time will be unstable and the soil around the tree will also be contaminated. You ask about a replacement for the Silver Birch Tree and the Mountain Ash (Sorbus Aucuparia) is a beautiful tree, flowers in the summer, beautiful red berries in the autumn and will grow to a height of approximately 25 feet. Or, you could plant a Laburnum Tree and the variety I would recommend is Watereri Vossii.

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Kenneth Young and Michael Collings both ask...

I just cut an 8" diameter branch from silver birch is there any way of stopping the bleeding?

Bill replies...

Quite a number of trees such as Acers, Birch and Vines can bleed badly if pruned in the springtime when the sap is beginning to rise and for this reason these trees are far better being pruned in the autumn time when the tree is becoming dormant and the sap is not rising. Whilst your Silver Birch is now bleeding profusely in time this will cease but unfortunately it can weaken the tree. As mentioned above you are far better pruning during the autumn time.

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Karen Dunne asks...

Hi there Bill my neighbour has planted a Silver Birch tree within 2 ft of the side of my house and it has grown well over the height of the house and is getting out of control. It is leaning on the brick wall in front of it which is causing it to crack (so leaning away from the house slightly) although the wall is attached to my house. The soil is a loose granular fill so there are no soil shrinkage risks. Do you think it could cause any damage? Thanks

Bill replies...

Your neighbour's Silver Birch tree Karen must be at least 30 feet tall and will grow to a height of 60 to 100 feet in time and I do feel that you need to take this into account when a decision is made in what to do with the tree. Two feet is very close to the side of your house and even though it has been planted in loose granular soil I feel that there is a risk of the roots damage the foundations of your house. Also again with the tree being so close to the house if the main branch breaks off during extreme windy conditions this again could cause damage to your property. I personally would recommend that you and your neighbour obtain on the spot advice from a qualified Tree Surgeon.

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Anthony York asks...

I have just been givern a 30ft plus Silver Birch it turned up with a root ball about a metre in diameter and the hole that it was planted in was a bit larger than that. The soil it's planted in is perfect soil. My First question is what's its chances of survival and my second question is, is there any way I can help it survive? I have giver it a good watering every other day but don't really know how much water to give it?

Bill replies...

If you have quite a large root ball your Silver Birch may survive Anthony but as you say 30 feet is a very tall tree to transplant and I feel that firstly to give your Birch a chance of establishing itself you will need to support the tree with solid stakes/supports. You ask about watering and watering will play an important part in the survival of the tree - especially if we do have a very hot summer. There is no need to water every other day, wait until the top few inches of the soil has dried out before giving the tree a thorough watering. As mentioned above the survival of your tree will depend on summer weather conditions and also the size of the root ball.

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Sue Rhodes-Hodgkiss asks...

We have a small garden and so we bought a dwarf Silver Birch about 8 years ago it is approx. 10-12ft high. There is a branch which makes the tree look lop sided and we would like to remove it. When is the best time to remove it and what do we treat the cut with afterwards. For when we move house we would like to take a cutting from this branch is this possible and what do we do with it?

Bill replies...

Silver Birch Sue is one of the trees which do bleed profusely if they are pruned when actively growing and you would be far better pruning during late autumn when the tree is becoming dormant. However this time of year (February) your Birch Tree will still be dormant and providing that you carry out the pruning immediately you can prune off your unwanted branch without causing any damage to your tree. If necessary you can treat the cut with a tree sealant such as Arbrex. With regard to taking a cutting from your tree, Silver Birch propagation is very difficult unless you have facilities such as a mist propagation/fogging unit and, the easiest method is from seed.

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Wilf Ring asks...

I have a silver birch in my garden and hope to do some building work fairly close by. The tree is about 15 years old, about 15-20 feet high with a spread of perhaps 10ft. It was planted in made-up ground below which (after about 0.5-0.6m) we have quite firm clay. Could you please advise how deep its roots might be so I can assess depth of foundation and whether or not to proceed.

Bill replies...

Although Silver Birch are not as troublesome as trees such as Willows and Oak Trees Wilf they will grow to a height of 60 to 100 feet and you must bear this in mind when assessing the depths of the foundations if you want to keep the tree in that particular part of the garden. You mention that your soil has quite firm clay and problems can arise in very dry summers when the clay begins to crack and causes subsidence - the roots will then penetrate through the cracks looking for water. It is difficult to give you a precise answer with regard to what damage the tree can do your foundations and it is always worthwhile obtaining a second opinion from a Tree Surgeon.

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Alasdair Muir asks...

I planted a silver birch tree early last year which is about 6ft tall. Due to the terrible weather conditions most of the winter the tree has been surrounded by water, has it got a chance of survival?

Bill replies...

I am afraid Alasdair that Silver Birch do not like waterlogged conditions and if this is going to be problematic every year I feel that if it is possible I would transplant your tree before it comes into leaf into a drier part of the garden. If this is not possible you will need to channel off any surplus water around the Birch Tree but, as mentioned they do prefer a well drained soil.

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Sue Blight asks...

I've just found this page and very pleased to have read your replies to Patricia et al re: silver birch. I have two beautiful and healthy 'spade' (as in a pack of cards) shaped silver birches about 15 years old. They are now so tall (at least 50 feet) I worry that they will be blown over as they are exposed to strong winds here near the Fens. Can I have their top THIRDS cut without causing die back or other permanent damage? Also I am wondering if winter (before end of February) is also a good time as I've missed Spring? I am keen to reduce their height to the level of the trees behind them (about 20 feet away to the east). Thanks so much

Bill replies...

The correct time Sue for pruning your Silver Birch trees is autumn time - when the sap is not rising - and the reason for this is that Silver Birch do bleed profusely when the sap is rising. Silver Birch are beautiful graceful trees and I feel that it is important when pruning that care is taken to avoid your tree losing their graceful shape. You ask about pruning in February, your trees will still be dormant and the sap will just be beginning to rise so you will probably be able to prune your trees. I do feel however that it would be worthwhile to obtain a second opinion from a Tree Surgeon who will be able to give you advice on how and where to prune.

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Linda asks...

We have a silver birch tree approximately 40/50 feet high and within 2 metres of our house. We would like to take it down are we likely to encounter heave problems?

Bill replies...

I would be inclined Linda to obtain 'on the spot advice' from a Tree Surgeon with regard to cutting your 40/50 foot Silver Birch Tree. Being only two metres away from your house is very close and I feel that you have made the correct decision in having the tree taken down, taking into account that the tree could grow to a height of 100 feet. However, there is a possibility that there maybe a Tree Preservation Order on your tree but the Tree Surgeon will be able to give you advice on this matter.

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Debbie asks...

Can I successfully transplant a thirty foot Silver Birch Tree?

Bill replies...

I am afraid that it is going to be nigh on an impossible task Debbie to dig up a thirty foot Silver Birch Tree and transplant it successfully in another part of your garden. You would need a JCB digger to dig out a large root ball and there is also the fact of supporting your tree when you have transplanted. I feel that you would be far better to purchase a small Silver Birch to plant in your desired spot in the garden.

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Pete asks...

We have four silver birch trees at the bottom of our garden that are taller than our house and the pub behind. When we have strong winds these tree tend to move quite a lot and make my wife nervous. Are Silver Birch very tough when it comes to wind and is there anything we can do to stop them getting any taller or to reduce there present height?

Bill replies...

Silver Birch are quite tough trees when it comes to withstanding strong winds Pete but it is going to be very difficult to stop the trees from growing taller unless pruned and with Silver Birch being a graceful tree, care needs to be taken with pruning to avoid the tree losing its shape. Silver Birch do suffer from bleeding which may cause die back and reduce vigour and therefore autumn time would be the preferred time to prune your trees when the sap is not rising.

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Mark Sales asks...

Hello Bill, we have just moved house and we have a garden of 60 x 40 foot which backs onto fields. I am a very new but enthusiastic gardener. I want to plant a Silver Birch at the far end of the garden facing the fields. Is the Silver Birch hardy enough to plant facing open fields, if not what tree do you recommend? Should you recommend a Silver Birch at what depth do I need to plant it correctly and what procedures should I make to plant it? Your advice would be invaluable to me.

Bill replies...

The Silver Birch (Betula Pendula) is a beautiful and graceful tree Mark and will grow in a wide range of soils providing that there is no water logging and would be ideal to plant at the rear of your garden. With your garden backing onto fields you will need to be aware of the damage caused by rabbits and the trunk of your tree will have to be protected. With your garden being quite long an alternative to planting the one specimen of Silver Birch you could plant a coppice of Silver Birch saplings which would be ideal in encouraging bird life to your garden. The saplings are easily obtainable from Garden Nurseries and now is the time of year - weather permitting - for planting to take place. (January)

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Gemma asks...

I have a silver birch tree in my garden. It is slowly growing closer to the house. If I cut off some of the branches will this slow the growth of the roots?

Bill replies...

By pruning back your Silver Birch Tree Gemma you will cut down the water requirements of the tree which, in turn will help to cut down the risk of root disturbance to your house foundations. However, long term this tree could grow to a height of sixty feet plus and depending on how near to your house the tree is will depend on whether or not you decide to have the tree removed.

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Claire asks...

We have just moved into a new house with a smallish (about 10m wide by about 8m deep) garden which we have laid to lawn for the children and plan to put a large climbing frame in the middle. I'd like to plant a tree in the top right hand corner, but it can't be too big or too spreading or it will get in the way of the climbing frame! The garden is fairly boggy and gets quite a bit of wind. I don't like acers, and don't want a cherry in case it attracts wasps: I was wondering about a silver birch but am concerned that it might get too big and unmanageable. Would a silver birch do in my garden and, if not, what else could you recommend?

Bill replies...

The Silver Birch Claire is quite a shallow rooted tree and would not be the ideal plant for a boggy garden. There are however trees which you could plant such as the Alder - which loves a wet garden. There is the Common Alder (Alnus Glutinosa) and there is the Golden Alder (Alnus Glutinosa Aurea) which as the name suggests has a beautiful golden leaf and will grow to approximately twelve feet. You could also plant the Mountain Ash (Surbus Aucaparia) which will tolerate a wide range of soils. And there is also the Laburnum Tree which again will tolerate a wide range of soils - but beware if you have children the seeds are poisonous. Of the three trees named my personal choice would be the Golden Alder.

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Matthew Green asks...

I am looking for a tree with the shape of a golden willow but only half the size, suitable for a garden. Can you help me to identify one please?

Bill replies...

One of my favourite weeping trees Matthew is the Silver Birch and the variety I would recommend is Betula Youngii and another beautiful tree is the Falca Acacia (Robinia) but the variety I would choose is Frisia which has beautiful yellow golden foliage and will grow to approximately 25 feet. There is also the range of Sorbus (Mountain Ash) and Sorbus Aucuparia which again will grow to approximately 25 feet and for a small garden I would choose Sorbus Hostii which will grow to approximately 12 to 15 feet.

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Roy Gilmore asks...

I help out at a school with the veg garden, recently we were gifted 10 of each of, rowan, wild cherry and silver birch trees. Could you tell me the correct planting distances for these trees and any other basic things we should do? Many thanks

Bill replies...

The planting distance between trees Roy is determined by the height the trees are going to grow to and the types of trees you are planting and the planting distance is approximately half the height the trees will grow to. The Rowans will grow up to ten to fifteen metres high - Wild Cherry (Prunus Avium) approximately ten to thirteen metres and, the Silver Birch fifteen metres plus. For example if you plant a Silver Birch next to a Rowan you will need to calculate roughly to what height these two trees will grow and then divide by two. At the early stages of growing this means that there is quite a gap between the trees but, you can also underplant with a range of shrubs such as Viburnums which will bridge the gaps. If however you want to plant these three trees into a small woodland copse you will be able to plant at a closer distance

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Bev asks...

We planted a silver birch last autumn which seems to be establishing itself well, however over the last 6 weeks or so many of the leaves are going yellow; we have had a fair amount of rain so it can't be that the ground is too dry. I know they will go yellow in autumn but surely not in June?! What is the reason for the yellow leaves and is there anything we can do to remedy this? Thank you.

Bill replies...

Due to the adverse/wet weather this summer Bev your Silver Birch is probably suffering from waterlogged conditions which will cause yellowing of the leaves and this is happening to a wide range of newly planted trees and shrubs. Silver Birch do prefer a reasonably well drained soil and I am sure that the high rainfall is the main contributor for the yellowing of your Silver Birch leaves.

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Gina Souter asks...

What is the liquid that drips from my Silver Birch in the spring?

Bill replies...

The usual cause for drips appearing on the branches of Silver Birch early Springtime Gina is due mainly to the pressure of sap within the tree. Too much root and sap pressure causes drips to appear from the stems. This quite often happens when you have very warm springtimes and the sap is actively flowing within the tree.

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Norma Kelly asks...

We have a Silver Birch Tree in our back garden, it is about twenty years old. I would be most grateful if you could tell me if the roots from a Silver Birch Tree could be dangerous to the foundations of our house. Thank you.

Bill replies...

The roots of the Silver Birch will in no way be as vigorous Norma as the roots of the Oak and Willow Trees. However an established tree such as Silver Birch will have a large root system to support and anchor the tree and supply nutrients and water to the leaves. A lot will depend on how far the tree is situated from the house and the general method used is that if a tree grows to a height of twenty feet it should be planted twenty feet away from the house but, as you will be aware, there are numerous trees planted closer to houses. The damage to the foundations is caused during very dry summers when the roots are actively looking for water which they will take from the foundations and surrounding soil.

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Patricia Bear asks...

I have a lovely row of Silver Birch trees in my front garden, but they are getting very tall and wanted to know what time of the year should I have the tops cut as I do not want to kill them by having it done at the wrong time of year.

Bill replies...

Silver Birch is one of the trees which bleeds profusely if pruned in the Spring and therefore the correct time to prune your Birch is in the Autumn Patricia. The Silver Birch is a very delicate and serene tree and my advice when pruning is do not prune them back too hard (not short back and sides)! You need to ensure your trees keep their natural flow.

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Pam Buchanan asks...

I have a large silver birch which is not a particularly attractive specimen due to poor pruning by its previous owner. This summer after a prolonged period of no rain all the leaves shrivelled and are now just hanging brown and dead. I do not want to remove it if there is a chance it will recover. It is planted on a south west facing slope. We have also had episodes of honey fungus a couple of feet away from the tree which I think are due to a dead shrub in the hedge. There is nothing around the immediate perimeter of the birch though. Should I leave the birch in place to see if it will regenerate in Spring or should I cut it down? I have a conservatory within falling distance of the birch so am somewhat concerned as to what to do for the best.

Bill replies...

If the leaves of your Silver Birch have dropped prematurely due to last year's hot summer Pam I feel that this coming Spring your Silver Birch should come into leaf again but there is a good chance there could be some die back of the main stems and branches and I would wait until Spring before taking any drastic measures. If however in the Spring there is substantial die back of the main branches this could quite easily have been caused by the Honey Dew Fungi and you will need to take this into account when making a decision about removing the tree.